1. Field of the Invention
This invention relates to an apparatus and method for data processing for IC tags and an image forming device such as a label printer. In particular, the invention relates to an apparatus and method for data processing for IC tags by which electronic information is read from and/or written to IC tags moving in a given direction, the IC tags being transported by a conveying medium on which they are mounted, and an image forming device with the data processing apparatus for IC tags.
2. Prior Art
A wireless communication device comprising a storage device, a transceiver, and an antenna is a semiconductor device from/to which contactless reading and/or writing of electronic information can be performed, which is generally called a Radio Frequency Identification (RFID) device. RFID devices are used, embedded in various kinds of IC cards such as credit cards. Recently, it has been proposed to use the RFID devices for management of commercial goods by embedding them into labels tagged to commercial goods, recording information about the goods electronically onto them, and reading the information from them as required.
To read and/or write electronic information from/to such an RFID device (hereinafter referred to as an IC tag), a system is known in which a conveying medium such as recording paper on which IC tags mounted by bonding and other means is allowed to pass through a reader/writer which performs reading and/or writing of electronic information, electronic information is transmitted and received between the antenna of the reader/writer and the antenna of each IC tag, and reading and/or writing of electronic information from/to the IC tags will be performed in a contactless state.
Some reader/writer of this kind quickly reads and/or writes electronic information from/to IC tags mounted on a conveying medium, arranged in multiple rows along the direction in which the conveying medium moves. In this case, the plurality of IC tags on the conveying medium are sequentially identified and electronic information for each identified IC tag is read from and/or written to each IC tag. To do this, the antenna of the reader/writer is moved in a direction orthogonal to the direction of moving of the IC tags to sequentially identify the IC tags arranged in multiple rows; this mechanism is disclosed in Japanese Laid Open Patent Publication No. 2003-300356.
A conveying medium on which IC tags are mounted, arranged in multiple rows and columns along the direction in which the conveying medium moves is also known, which is disclosed in Japanese Laid Open Patent Publication No. 2003-331220.
Moreover, in sorting a device that uses IC tags for sorting packages, an antenna device allowing for reliable reading of electronic information from IC tags is disclosed in Japanese Laid Open Patent Publication No. 2004-244140. This antenna device consists of two coil antennas placed to surround a conveyer belt for conveying packages and the two antennas extend in the direction of conveyance and are placed asymmetrically to widen the area where communication with IC tags is possible in the conveyance direction and ensure longer communication time during which more read operations are performed.
Furthermore, when the conveying medium on which IC tags are mounted is moved at a constant speed, if the amount of data for electronic information to be read from and/or written to an IC tag is great, reading and/or writing of the information may be uncompleted during the passage of the IC tag through the antenna coverage of the reader/writer. When a plurality of IC tags exist in the antenna coverage of the reader/writer, an IC tag for which reading and/or writing of electronic information should be performed cannot be identified and a communication error may take place. The use of a smaller antenna for countermeasures against such error may result in incompletion of reading and/or writing of electronic data during the passage through the antenna coverage. To address such a problem, a system in which multiple readers/writers or their antennas are provided and one of them is selected according to condition is disclosed in Japanese Laid Open Patent Publication No. 2004-082432.
The above prior art readers/writers that read and/or write electronic information from/to IC tags each bring about disadvantages below: need for the mechanism to move the antenna orthogonally to the direction in which IC tags are conveyed (Japanese Laid Open Patent Publication No. 2003-300356); provision of multiple antennas for countermeasures against communication errors which may occur when a plurality of IC tags exist in the antenna coverage of the reader/writer; and need for communication error preventing measures such as providing more spacing between IC tags on the conveying medium in the conveyance direction.